amosblomqvist
65dfda2342
The converged variant read as two arrows feeding one point; the two- complete-arrows variant as two arrows next to each other, not coherent. Owner withdrew the double-shaft idea entirely (2026-09-15); dashed was already rejected 2026-09-14. Both relation types draw the same plain single arrow again. Kept: CanvasEdge.type plumbing from the snapshot (the next differentiator will need it) and the ArrowGeom named type. Removed: followsEdgeGeometry, the gap constants, the zoom-drift edge-path rebuild (edges are back to a single loop in buildGeometry), the ⟹ legend entry, and the glyph tests. Vision doc records the withdrawal and keeps the still-valid constraints. Gates: tsc, 429/429 tests, lint, build. Live: canvas coverage 0.477, no console errors, no legend remnants.
3.4 KiB
Vision — The edge glyph: follows vs supports
Ideation settled 2026-09-14. WITHDRAWN 2026-09-15: both shipped variants of
the double-shaft glyph (tails converging on a shared head; two complete arrows
offset ±half-gap) were rejected by the owner live — the first "two arrows
feeding one point", the second "two arrows next to each other, not coherent".
Dashed was already rejected 2026-09-14 (dash patterns crawl under the constant
screen-space stroke width). The relation still needs a differentiator —
approach open. The constraints below that are NOT glyph-specific still stand.
Companion: vision.md § "Edges" (the relation types) and § "Rendering".
One line (withdrawn): the two relation types become visually distinct —
follows renders as a double-shaft arrow (two parallel tails side by
side, the implication glyph ⟹), supports stays a single line. Arrows
keep their existing direction: prerequisite → dependent.
Why double-shaft (DECIDED 2026-09-14)
- Semantically exact.
followsmeans prerequisite ⇒ successor — derivability. The implication glyph is the relation; nothing encodes "derivable from" more literally. - Weight where the structure is. The DAG backbone (
follows) gets the heavy glyph; the majority relation (supportsis over half of all edges) stays light. The structural skeleton reads first. - Shape survives everything color can't. Cluster regions already own the color channel; a shape code collides with nothing and survives colorblindness.
- Scale-stable. Pure geometry degrades nowhere — see the rejected alternative below.
Why not dashed (rejected 2026-09-14)
Dash patterns break under our constant screen-space stroke width: the dash array is re-projected across zoom levels, so the pattern pops and crawls instead of scaling cleanly (the same class of artifact as the non-integer blur radii). And with supports the majority relation, dashes would dominate the canvas rather than mark the exception. Dashed = wrong twice.
Geometry
The renderer is the custom 2D canvas; edges draw in the edge layer with shafts + arrowheads from arrowGeometry (sigma-style head, prerequisite → dependent). For follows:
- Both shafts offset along the edge normal by a fixed screen-space gap.
- REVISED 2026-09-15 (owner rejected the first cut): the converged variant — two tails merging into one shared arrowhead — read as two arrows feeding a single point, not as parallel strokes. The glyph is two complete regular arrows (own shaft + own head each) translated ±half-gap along the normal: parallel shafts AND parallel heads, nothing converges.
- The gap is proportional to the constant stroke width — a constant visual ratio at every zoom level.
- No LOD collapse (withdrawn 2026-09-14). The earlier idea of collapsing to a single shaft below a stroke-width threshold assumed width shrinks with zoom — it doesn't; stroke width is constant on screen, so the double shaft renders identically at every zoom level. Simpler than proposed: nothing to gate.
Legend and scope
- Add a legend entry to the existing graph legend:
⟹ follows · → supports. - Main graph view only. The plan-block renderer (dagre) is untouched — the plan DAG is single-relation, so there is nothing to distinguish there.
Lane
lh-graph's renderer files (graph-canvas.ts, graph-view.tsx). Not assigned, not scheduled.